DESCRIPTION (Applicant's Description): The renewal of this ongoing postdoctoral training program for Years 17-21 will support six (6) postdoctoral fellows. The training program provides research training essential to the academic and research base of DNA damage response. The goal is the training of independent investigators on the molecular basis of DNA damage response and on the ways this knowledge can be translated to new cancer therapies. It emphasizes direct research experience in the laboratory and is supplemented by formal courses, seminars and conferences, as well as by exposure in the clinical environment. The revised program offers training adapted to the emerging requirements of Cancer Research and takes full advantage of the available resources within the Jefferson Campus. It includes training on the essential aspects of DNA damage response such as signal transduction, DNA repair, checkpoint activation, apoptosis, and response modifiers. A unique feature of the program is the exposure of trainees to the clinical environment and their assignment to clinician scientists working at the forefront of clinical cancer research. Applicants must have a Ph.D. in the biological, chemical or physical sciences or an M.D., D.O., D.V.M., or comparable degree. Candidates with a Ph.D. degree must be graduates of outstanding programs, have a proven record of research accomplishments during their predoctoral work and have a clear interest in a research career. The training program consists of 2-3 years of direct laboratory experience under the supervision of one of the preceptors. The training emphasizes hypothesis oriented research, the development of an appropriate experimental design and the use of modern techniques to address pertinent issues of cancer research. Trainees publish their results in peer-reviewed scientific journals. The specific areas of research represented by the program faculty are emphasized. Following completion of the program trainees will be prepared to enter independent research careers in modern aspects of cancer research in a university, government laboratory or industrial research setting.